1. Field of the Invention
The present invention relates to a vehicle-use electric rotating machine mounted on a vehicle such as a passenger car or a truck.
2. Description of Related Art
It is known to provide a vehicle generator with a power conversion apparatus including a power converting section having a plurality of switching elements to rectify the output voltage of the vehicle generator. For example, refer to Japanese Patent No. 4275704. The power conversion apparatus described in this patent is configured to control each of its switching elements such that the diode conduction state ends after an elapse of a predetermined off-ensuring time from a time when the switching element is turned off, so that a current is prevented from flowing from a vehicle battery to the armature winding of the vehicle generator.
However, the power conversion apparatus as described in the above patent has a drawback in that it exhibits large loss due to the off-ensuring time, which leads to reduction of efficiency of power generation. The loss during the off-ensuring time in which a current flows through the diode is larger than that during a time period in which a current flows through the switching element which is turned on. To reduce the loss, it is preferable to shorten the off-ensuring time. However, if the off-ensuring time is excessively shortened, it may occur that a timing at which the switching element is turned off becomes later than a timing at which the diode conduction state ends.